Buying second hand programs for a mac?

I found a guy on craigslist who wants to sell the following items: OSX 10.5 original apple restore disks for intel macs which include brand new full version of iLife 09 sealed not used. I have an imac mini 1.66 core duo. My question is can I use these disks to load the programs on my mac or are they configured specifically for his machine? He wants $50 for them which is considerable cheaper than buying them new… but can I use them?